The 2008 Mercedes-Benz GLs in this analysis were driven mostly on the highway at an average speed of 71 miles per hour (about 42.1 percent of the miles driven). The rest of the miles were in the city (21.7 percent), in heavy traffic (5.7 percent), and in the suburbs (0 percent).

In addition, the average 2008 Mercedes-Benz GL in this analysis was driven on flat terrain with a light foot and the AC not used at all.

2008 Mercedes-Benz GL Gas Mileage (MPG)

Unlike other fuel economy surveys, TrueDelta's Real-World Gas Mileage Survey includes questions about how and
where a car was driven. So you can get an idea of the Mercedes-Benz GL's
real-world MPG based on how and where you drive a car.